This invention relates to a method of preparing high solids liquid starch using a modified two step batch cooking procedure.
The ability to provide high solids liquid starch products which are stable and readily useful is highly desired for various end uses. Such starch products have been available and produced for many years in continuous cooking processes using a heat exchanger or jet cooker. Illustrative processes and equipment used therein are described in U.S. Pat. No. 2,919,214 issued Dec. 29, 1959 to O. Etheridge; U.S. Pat. No. 3,133,836 issued May 19, 1964 to V. Winfrey et al.; U.S. Pat. No. 5,131,953 issued Jul. 21, 1992 to J. Kasica et al. and in Chapter XVIII of Starch:Chemistry and Technology, edited by Roy Whistler et al., 1984, pp. 555-557.
While the continuous cooking processes as described above, do provide high solids starch products, they involve the use of high pressure steam and specially modified jet cooking equipment and conditions which may not always be available. Furthermore, in some situations it may not be economically feasible to build and install the needed equipment. In such circumstances, standard batch operations may be employed, however, they usually require special mixing equipment such as "gate" or "racker arm" type agitators in order to provide high solids starches. When using standard batch cooking processes with other common or conventional mixers, the desired levels of high solids content, i.e. 15% or more, cannot be attained because the cooked starches have such high final viscosities and peak viscosities during cooking that they are not easily mixable, pumpable, or handleable. This is especially true in batch tanks containing turbine type agitators which can be easily "overloaded" by the extremely high peak viscosity during the cooking process. In this instance the drive motor might "burn out" or the agitator could either "bend" or "bore a hole" in the starch gel produced.
Accordingly, there is need for a process of providing stable, high solids liquid starch products wherein the use of special and costly equipment such as involved in continuous cooking operations are not required.